GV led the "Series D" round of funding — the fourth injection of money from institutional investors — but Currencycloud also attracted money from existing investors, including Sapphire Ventures, Notion Capital, Japanese e-commerce giant Rakuten's fintech fund, and Anthemis.

The latest investment takes the total raised by the 5-year-old business to £44 million. Currencycloud last raised money in June 2015. CEO Mike Laven told BI this week: "We don't give the valuation but the actual valuation has more than doubled since the last round."

Currencycloud offers firms a simple piece of software that lets businesses send money internationally in a simpler and cheaper way than banks do. Best of all, it plugs in to their existing systems through something called an API — a little like a digital lego brick you can tack on to carry out a specific function. Just as with lego, the individual bricks can be used to build something entirely different. Many modern companies come up with their product by plugging different APIs together in new ways.

Laven says Currencycloud's focus on APIs is what attracted GV. He said: "GV looked at that and looked at empowering developers and making it easy for them to tie up to global services and said that is consistent with our view of a world, a tool that's part of globalization. That was part of the theme of the investment.

"We've been saying all along, we're not just a payments company, not just an FX company. We're a platform with API access to the world of global payments."

GV partner Tom Hulme said in a release announcing the investment:

"We believe in empowering developers by making it easier for them to add scalable services to their products, ideally with simple APIs. Currencycloud is the leader in providing cross-border payment services in this manner, a real need as companies globalize."

Over 200 companies use Currencycloud's technology and more than $25 billion has been sent across its network. It works with leading UK fintech businesses such as mobile remittance business Azimo, crowdfunding platform Seedrs, and foreign exchange card Revolut.

Laven says Currencycloud will use the funding to expand in the US, where it already employs 12 people in New York, and in Asia, where it currently has no presence.

"When we talk about global expansion, what we talk about is increasing the scalability of the platform, building out our operation in North America, and establishing an operation in Asia. Then that becomes a 24/7 operation and that takes investment in order to keep that service for the customers"

He added: "The US, for what we do, is dramatically underserved in terms of B2B payments. I would look at it as a frontier market in some ways."

Laven says the looming start of Brexit negotiations and what that might mean for the London-headquartered company did not come into conversations when raising money.

"We didn't have any Brexit push back anywhere," he said. "We recently signed more clients in France, more in Spain. I think the big growth potential is outside of the EU. If we do need to become regulated within the EU to provide our services to our customers then we will that."

He added: "The UK has been, and will continue to be, the foreign exchange capital of the world. My greatest concern is only about access to staff. What drives our business as a hub is the access to some of the best people in the world. That has to continue. But I don't see the UK losing its fintech pre-eminence."